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Simulating a time-domain reflectometry (TDR) response
A time-domain reflectometer (TDR) is an electronic test instrument that characterizes a transmission line circuit by applying a fast voltage step and observing the reflected signal that occurs when the step encounters an impedance change. From the TDR response, one can determine the characteristic impedance level of the transmission line at different locations and detect the presence of parasitic inductance or capacitance along the line.
Can XMODEL simulate this time-domain reflectometry (TDR) response of a transmission line circuit? Can you show me an example?
It's easy. All you have to do is use a TDR model, as shown below, to drive one end of the transmission line circuit and observe the response at the node labeled 'src'. The combination of a 'pulse_gen' primitive and a 'transition' primitive generates a single 1-V step at time 0 with a 50-ps rise time, applied through a 50Ω series resistance and a 50Ω transmission line.
Below is an example demonstrating the measurement of the TDR response of a transmission line circuit using this model. The example circuit consists of transmission line segments that have different characteristic impedances and lengths, as well as parasitic inductance or capacitance at their junctions. From the simulated response, one can identify the characteristic impedance value of each transmission line segment and determine whether parasitic inductance or capacitance is present at each junction.
Attachment: TDR_ex_20251029.tar.gz
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